Cimetidine and renal allograft rejection

Cimetidine, an H2 receptor antagonist, has gained acceptance as a drug capable of preventing gastroduodenal complications in renal transplant recipients. In several reports, cimetidine's immunoregulatory role has been questioned and its possible interference with graft acceptance has been observed. Two kidney allograft recipients are reported here, in whom cimetidine administration was associated with acute graft deterioration, which was completely reversed when the H2 receptor blocker therapy was discontinued. The observations support the view that the drug has an immunological, rather than nephrotoxic, effect. Caution should be exerted, at this stage, with respect to the use of cimetidine in renal transplant recipients.